Photolithographic processing is commonly utilized for patterning materials during semiconductor processing. In photolithographic processing, photoresist is exposed to patterned radiation and then developed to form a patterned photoresist mask. The pattern of the photoresist mask may be subsequently transferred to underlying materials with one or more suitable etches. Alternatively, or additionally, the photoresist mask may be utilized to block a portion of the underlying substrate during implant of dopant into the substrate.
It is often desired to form the patterned photoresist mask to have vertical sidewalls extending from the underlying substrate. A problem that may occur during photolithographic processing is that the sidewalls may only be vertical along the upper portions, and may have non-vertical excess material at the interface of the photoresist mask and the underlying substrate. Such excess material may be referred to as foot regions at the base of the photoresist mask. The foot regions complicate subsequent utilization of the mask, regardless of whether the mask is utilized to pattern an etch or is utilized for patterning a dopant implant.
It is desired to develop methods for treating photoresist masks which remove the foot regions.